1. Field of the Invention
The present invention relates to a punch of a compression molding machine, the punch including a punch tip portion and a holder unit for holding the punch tip portion.
2. Description of the Related Art
There has been conventionally known a configuration of a punch of a compression molding machine, which includes a punch tip portion and a holder unit for holding the punch tip portion. A punch of this type in the compression molding machine is conventionally attached by means of a structure in which a punch tip portion is abutted against a holder unit provided with a male thread, and then the holder unit is screwed with a cap provided with a female thread, so as to fix the holder unit and the punch tip portion to each other (refer to Japanese Unexamined Utility Model Publication No. S62-34995, for example).
However, this structure requires a tool such as a wrench for screwing the cap to the holder unit. Unless the cap is tightly screwed with use of such a tool, the cap might be loosened while the compression molding machine is in operation. Further, it is necessary to control tightening torque so as to be equally tightened regardless of who screws the cap with the holder unit. Moreover, the cap needs to be rotated for several times for screwing. As a result, in a case where this structure is applied to a compression molding machine including a large number of punches, it takes enormous time to assemble a mold tool therefor.